Mechanisms which control the extent of a given alcohol drinking session are unknown. How various Central Nervous System (CNS) processes related to motivation and reinforcement interact in this control are only beginning to be examined. In this competing renewal, we are proposing to continue our studies on the role of the mesolimbic dopamine (DA) system in this regulatory process. This DA pathway has been implicated in reinforcement/reward mechanisms for several classes of abused drugs and the data from the prior grant period suggests that ethanol also utilizes this pathway for at least part of the processes which may regulate ethanol consumption. Nine experiments are proposed. In all of the studies, we will employ rats that are self-administering ethanol following initiation with the sucrose- fading procedure developed in our laboratory. When the rats are initiated, guide cannula will be placed so that various agents can be microinjected into specific brain regions prior to or during self-administration session. Five studies will continue to explore the relation of the mesoaccumbens DA pathway in ethanol self-administration using D1 agonists and antagonists, GABA agonists and antagonists and opiate agonists and antagonists. Two will explore other components of the mesolimbic DA system, the frontal cortical projection field and the amygdala. For these studies dopamine agonists and antagonists will be employed. The last two will use procedures to determine the extent of conditioned stimuli in the regulation of ethanol drinking.